St. John’s Wort herb interactions?

Susana wrote to us asking “Can you take Red Clover and St John’s Wort together or in the same day?”
This is a great question, Susana! And timely as well as I just pressed my St. John’s Wort (Hypericum perforatum) (SJW) oil (check out the flowers, oil infusing and finished ruby red oil in the photo), so I’ve got SJW on my mind!
Pro – tip: SJW oils and tinctures should be bright red. If they’re not they were likely either not extracted well or they are old and the quality is waning.
Back to the question…The short answer is, yes, SJW and red clover (Trifolium pratense) are safe to take together. Now, for the details. . .
While most herbs are very safe with few herb – herb or herb – drug interactions, SJW is one herb that has been proven to interact with some substances. So, it is wise to consult with a professional herbalist before adding it to your regimen.
First of all, in any discussion involving SJW it is important to discuss quality. SJW grew in popularity so quickly in the late 1990’s that the demand was significantly larger than the supply for several years. Thus, there were a lot of products labeled SJW that did not actually contain any SJW! (Eeeek!) In addition to the quality of the raw material, the SJW dose and quantity of hyperforin (an important constituent in SJW) are important factors that effect the degree of potential interactions.
Hyperforin is an unstable constituent, especially when in solution such as in teas or tinctures. So, it is important to acquire a good quality product. My personal favorite SJW product is these tablets by Mediherb. Mediherb products are high quality, efficacious and practitioner only so you’ll need to consult with an herbalist to purchase them. That said, there are other quality products that are over the counter including these capsulesby Gaia Herbs.
When it comes to interactions, SJW has been highly researched (see page 36 of this excellent article from the American Herbal Products Association for more information) and there are two main ways SJW can interfere with drugs:
1. Metabolic or pharmacokinetic interactions: SJW interferes with drug metabolism in the liver and decreases plasma levels (and therefore efficacy) of some drugs (up to 50% of drugs!). This is a similar mechanism as grapefruit but with the opposite result (grapefruit increases plasma drug levels).
2. Pharmacodynamic interactions: SJW is thought to alter the effects of prescribed antidepressant drugs, specifically the selective serotonin re-uptake inhibitors (SSRI’s). Ask-the-herbalists has written about the effect on birth control pillshere.
Keep in mind that based on a very large body of evidence (over 14,000 patients!), Schulz (2006) concluded that the incidence of adverse effects was ten times less with SJW as compared with conventional antidepressant drugs.
Now, red clover is a much less researched herb. However, we know it contains phytoestrogens. Phytoestrogens are non-steroidal plant constituents with mild estrogen-like activity thought to exert their effects by competing with estradiol for binding and activation of estrogen receptors (thus potentially decreasing the effect of estradiol). Phytoestrogens are prolific constituents found in many common foods including tea, coffee, some beers, legumes, nuts, seeds, grains, oils and fruits. Additionally, there is abundant clinical data demonstrating the safety of phytoestrogens.
There is evidence that SJW also effects hormone levels — a few studies show that SJW decreases the severity, frequency and duration of hot flashes. SJW may be altering the hormone metabolism in the liver. So, while red clover contains phytoestrogens that bind to estrogen receptors, SJW alters the liver’s ability to metabolize constituents, drugs, hormones and more. Thus, these two herbs act on different systems in the body and are safe when taken together. So, while it is important to exercise caution when taking SJW with many drugs, herb – herb interactions are extremely rare.
Salut, Amy
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